Remember to cover the basics, that is, what you expected to happen and what in fact did happen. You don't know how to make a good report? See
https://orgmode.org/manual/Feedback.html#Feedback Your bug report will be posted to the Org mailing list. ------------------------------------------------------------------------ In the agenda buffer, I've called the `org-set-effort` function with the `e` key, and input "-" which is malformed. I did receive an error `Invalid duration format: "-"`, but the "-" has still been written in the entry as an effort property. As a consequence of this bug, opening the agenda buffer raise again the error `Invalid duration format: "-"` which results that the agenda buffer cannot be opened. The malformed line :Effort: - can only be found by a dichotomic search which is quite annoying. For a similar issue, see here https://emacs.stackexchange.com/questions/36111/invalid-duration-format-org-agenda/53637#53637 Maybe other functions have the same behavior (writing malformed value on the agenda even after reporting the error). Emacs : GNU Emacs 26.3 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.8) of 2019-10-22 Package: Org mode version 9.1.9 (release_9.1.9-65-g5e4542 @ /usr/local/share/emacs/26.3/lisp/org/)